The present invention relates to a circuit for dispensing windshield washer fluid for a vehicle, such as a motor vehicle.
Conventionally, a circuit for dispensing windshield washer fluid includes a storage tank for windshield washer fluid which is placed in the engine compartment of the vehicle, or in a free space of the fender of the vehicle, a pump optionally built directly in the storage tank, and a tube connecting the storage tank and the pump to the nozzles for spraying the windshield washer fluid onto the windshield of the vehicle or the glass lens of the vehicle's headlights, or to a nozzle for atomizing windshield washer fluid on the back window of the vehicle.
The nozzles are sometimes mounted on the support arms of the wiper blades or on the wiper blades themselves, and a portion of the tube is then located outside the vehicle.
Under these conditions, due to the fact that the nozzles and the outer portion of the feed tube supplying windshield washer fluid to the nozzles are not protected by the engine of the vehicle, the windshield washer fluid present in the nozzles can freeze in cold weather and due to the aerodynamic effect of the forward movement of the vehicle, making the nozzles unusable.
A simple solution to prevent the freezing of the windshield washer fluid in the nozzles and in the outer tube portion consists in completely purging the circuit for dispensing windshield washer fluid by returning it into the tank.
However, the disadvantage of this solution is that it increases the response time of the window washing function, especially when the tank and the pump are installed far from the nozzles.
The document DE 3840621 describes a circuit for dispensing windshield washer fluid comprising a valve making it possible to direct the windshield washer fluid to at least one nozzle when a feed pump supplying windshield washer fluid is activated, and allowing the windshield wiper fluid standing in a portion of the tube located outside, between the nozzle and the valve, to be discharged into the storage tank for windshield wiper fluid when the pump is stopped in order to prevent the fluid from freezing in cold weather. The valve consists of a movable part that occupies a different position depending on the pressure of the windshield wiper fluid, thus opening specific passages in order to make it possible to supply the nozzle with windshield washer fluid or to discharge the windshield washer fluid contained in the outer tube portion connected to the nozzle.
However, the design of such a valve is fairly complex and costly.